This research paper addresses the hypothesis that the incorporation of yellow-fleshed sweet potato powder (SPP) into yoghurt can enhance its physicochemical, microbial and textural properties while improving storage stability. This study aimed to develop a yoghurt product incorporating yellow-fleshed SPP and to evaluate its effects on physicochemical, microbial and textural properties during fermentation and a 28-day storage period. SPP was added at concentrations of 0%, 5%, 10%, 15% and 20% (w/v) to milk prior to fermentation. Parameters including pH, titratable acidity (TA), syneresis, viscosity, hardness, adhesiveness, colour attributes and microbial viability were measured. The addition of SPP positively influenced the fermentation process, significantly increasing total plate count, TA, viscosity and adhesiveness, while reducing pH, syneresis and hardness. Colour analysis showed that supplementation decreased L* values and whiteness index while increasing a*, b*, yellowness index and ΔE*, depending on the amount added. During storage, yoghurts with 5-10% SPP maintained superior textural stability, lower syneresis, minimal colour changes and preserved microbial viability compared to the control and higher concentration treatments. Otherwise, 15-20% additions resulted in reduced bacterial counts and destabilised gel structure. These results suggest that yellow-fleshed SPP acts as a natural stabiliser and prebiotic, enhancing yoghurt quality and storage stability. An optimal addition of 5-10% is recommended to maximise functional and sensory benefits without compromising product integrity, offering promising potential for the development of value-added, health-oriented dairy products targeting modern consumers.
Keywords: lactic acid fermentation; physicochemical properties; storage stability; sweet potato powder; yoghurt quality.